1. Field of the Invention
This invention relates to a multiple piercing apparatus, and more particularly to an apparatus for piercing sheet or plate material, such as a substrate or the like, by a piercing device such as a twist drill or punch assembly.
2. Description of Background and Relevant Information
In the manufacture of a substrate, it is generally known to form a perforation, such as a basis hole or the like, by a conventional type piercing apparatus such as a punch assembly or twist drill, which is adjustably fixed at a predetermined position. This includes a method of moving a workpiece itself for centering, and includes, in the piercing process of the above conventional method, initially printing a reference mark on a surface of the workpiece. Then, the workpiece is loaded on a piercing apparatus and moved to locate the mark adjacent the piercing assembly, so that the mark is viewed by an industrial camera for processing its image data in a microprocessor which communicates with a piercing mechanism, or the mark is manually viewed by an operator while using an optical instrument such as a reflex type sensor together with a fine control mechanism operated by hand. Through these methods of centering the mark, the workpiece is finally located at an accurate position substantially at the center axis line of the punch assembly or twist drill Then, the piercing is achieved by the punch assembly or twist drill.
Even though such piercing assembly is a multiple type, the above described steps, that is, the centering and piercing processes, are required for each respective piercing assembly.
In the above described conventional method, the workpiece itself is moved in the X-axis and Y-axis directions by clamping the workpiece on a work bed during its centering step. Therefore, it is only possible to treat a cut out type workpiece and not a continuous type sheet, making it impossible to make any piercing apparatus capable of handling a continuous type sheet in a conveyor type manufacturing line.
Therefore, it is an object of the present invention to provide a multiple piercing apparatus which is capable of accomplishing the necessary processes, such as centering and piercing, without any movement of the workpiece itself on the apparatus, thus making it possible to include such an apparatus in a continuous type manufacture line for a substrate.